Incandescent lamp



, No. 624,463. Patented May 9, I899.

E. F. DWYER.

INCANDE'SCENT LAMP.

. (Application filed 9, 1899.) (No Model.)

mass? fiverda M m UNITED STATES PATENT OFFICE.

ELMER FRANCIS DWYER, LYNN, MASSACHUSETTS.

INCANDESCENT LAMP.

SPECIFICATION forming part of Letters Patent No. 624,463, dated May 9,1899.

Application filed March 9 1 89 9 To all whom it may concern:

Beit known thatLELMER FRANCIS DWYER, a citizen of the UnitedStates,residing at Lynn, in the county of Essex and State ofMassachusetts, have invented certain new and useful Improvements inIncandescent Lamps; and I do hereby declare the following to be a full,clear, and exact description of theinvention, such as will enable othersskilled in the art to which it appertains to make and use the same.

My invention relates to an improved form of incandescent lamp, and moreparticularly to incandescent lamps provided'with coiled or loopedfilaments.

I am aware that it has been proposed to provide a support for thefilament in addition to that afforded by the leading-wires and thatlamps have been constructed wherein the loop of the filament has beensupported by an auxiliary support sealed in the glass at the end of theglobe, adapted to loosely embrace the filament or filament-section, sothat the filaments will be prevented from undue vibration and consequentbreakage. I am also aware of the common practice of making filamentswith a coil or loop at the outer end of the globe and in providing anauxiliary support attached to the coil, extending backward and sealed atits other end into the glass of the stem. My improvement contemplatesentirely doing away with these auxiliary supports and in attaching orsecuring by a suitable cement the coil or loop of the filament directlyto the stem of the lamp. The advantages flowing from this improvementare considerable and consist not only in the greatly-reduced cost andfacility of manufacture, but in the simplification of the lampstructure, the greater rigidity of support given the filament, theremoval of any obstruction to the radiation of the light from theincandescent surface of the filament, the considerably-increasedilluminating-surface of filaments for a given size of globe, and theuniformity of spherical and horizontal illumination.

My invention consists in the improvements hereinafter described, andmore particularly pointed out in the claims.

In the accompanying drawings, illustrating the preferred form of myinvention, Figure 1 Serial No. 708,336. (No model.)

is an elevation of my improved lamp; and Fig. 2 is a sectional elevationof the end of the stem in which the base A, globe B, and stem 0 are andwill preferably be of the form and proportions usual in incandescentlamps.

The filament D is provided with a return coil or loop extending backwardtoward the stem 0, to which it is directly and rigidly attached orsecured bycement E at a point preferably midway between the twoleading-wires d. This cement is the same as that now commonly used toattach the ends of filament to the leading-wires.

While the filament may be attached to the stem by cement in an y'desired. manner,'I prefer to provide the extreme end of the stem withrecesses of such form that the cross-section of the stem at this pointwill be of a dovetail form. This construction is illustrated in Fig. 2,wherein 0 indicates the stem shown in cross-section, the extreme end ofwhich, 0, is of a dovetail form, as described. The cement E, which isused to attach the filament to the stem at this point after hardening,closely embraces the dovetail end of the stem and is thercbyeffectuallyprevented from becoming disengaged therefrom.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent of the United States, is

1. An incandescent lamp ha'vinga stem and a coiled or looped filament,the coil or loop of the filament being extended backward toward the stemand attached or secured directly and rigidly thereto by cement,substantially as de scribed.

2. An incandescent lamp having a stem provided with a dovetail end and,a coiled or looped filament, the coil or loop of the filament beingextended backward toward the stem and attached or secured directly thereto by cement, which embraces the dovetail end of the stem, substantiallyas described.

In testimony whereof I afiix my signature in presence of two witnesses.

ELMER FRANCIS, DWYER.

Witnesses:

CHARLES H. CHASE, WEBSTER BRUCE.

